Q. Some time ago I wrote to you about a problem I was having with my car, a Buick Park Avenue, stalling in traffic.

My experience may help another of your readers. I took your advice and called Buick's 800 number to find out where to take the car. I was given the names of two dealer garages -- one where we have purchased cars in the past, so I had no reluctance about going there.

I am sending along a copy of the garage statement because it explains the problem better than I can. Also read the note about the computer installed earlier by another garage. I was told it was a genuine GM replacement. We just drove to South Carolina and back and had no trouble. R.J.B., Storrs. A. Calling the automaker's 800 number is a good bet in my book, so it's heartening to see it worked in your case.

The dealership's bill notes that the idle air control valve, idle air control motor and a shorted-out coil pack were replaced, either of which could induce stalling. The cost was $460.97.

The note at the bottom of the bill says the car has an aftermarket ECM, or engine control module. For another garage to call it a genuine GM replacement part, if it was a rebuilt module, is somewhat less than truthful.

Q. I have a 1990 Eagle Summit with 34,000 miles. Everything is going fine except the right CV joint, which I had to have changed due to breakage and leakage thrice since June 1993.

Mechanics have told me that such frequent CV boot problems may occur -- but thrice in a year? I do not have the warranty papers and I bought the car from an individual, not from a dealer. S.B., Willington.

A. Frequent changes on a boot for a CV, or constant velocity joint, can occur if the car is driven in rough off- road territory.

Take the car to an Eagle dealer to see if the boot being used is not correct for the car. I used to change CV boots 30 years ago, and they are rather tough items. They should last more than four months.